Optical fibers can be used as sensors to measure a temperature, a strain or other quantities, such as a vibration, a pressure or acceleration, based on a change of value in the intensity, phase, polarization, wavelength or transit time of light propagating through the fiber during its propagation. By way of examples, an optical fiber sensor can be used in minute and sensitive environments, such as in a human body so as to sense a blood pressure, a pulse rate or a temperature. Further, an optical fiber sensor can also be used to monitor conditions of harsh environments, such as wings of airplanes, wind turbines, bridges, large dams, oil wells or pipelines.